Aqueous solutions modeling

Semenova, M.G. (1996). Factors determining the character of biopolymer-biopolymer interactions in multicomponent aqueous solutions modelling food systems. In Parris, N., Kato, A., Creamer, L.K., Pearce, J. (Eds). Macromolecular Interactions in Food Technology, ACS Symposium Series No. 650, Washington, D.C. American Chemical Society, pp. 37 19. 

Yiacoumi, SKinetics of Metal Ion Adsorption from Aqueous Solutions Models, Algorithms, and Applications, Kluwer Academic Publishers. Norwell. MA, 1995. 

Candeias LP, Steenken S (1992b) Ionizing purine nucleosides and nucleotides and their components by 193-nm laser photolysis in aqueous solution model studies for oxidative damage of DNA. J Am Chem Soc 114 699-704... 

Geochemical modeling is often used to identify the compounds that primarily control the chemistry of arsenic in aqueous solutions. Modeling studies indicate that the arsenic concentrations of Kelly Lake, Ontario, Canada, are controlled by the precipitation and dissolution of Fe(II) arsenates rather than calcium or Fe(III) arsenates (Sadiq et al., 2002). The arsenic in the lake originated from runoff from the nearby Sudbury mining district and airborne particles from local ore smelters (Sadiq et al., 2002). 

ABSTRACT. An X-ray diffraction measurement has been carried out for a 3.9 mol% aqueous solution of TBA (tertiary butylalcohol) with an energy-dispersive diffractometer. Constant temperature molecular dynamics calculation has also been made for an aqueous solution model simulating the above-mentioned mixture. Both results suggest the formation of a fairly stable clathrate-like structure of water around TBA molecules. 

Herves R, Perez-Lorenzo M., Liz-Marzan L. M., Dzubiella J., Lu Y, and Ballauff M. Catalysis by metallic nanoparticles in aqueous solution Model reactions. Chem. Soc. Rev. 41 no. 17 (2012) 5577-5587. 

Due to its structure, the Achard model is a predictive model. Considering a mixed electrolyte solution (e.g. water-NaCl-KCl), it is possible to calculate the activities of all the species and constituents of the media, because the interaction parameters are from binary water-electrolyte systems. However, it is an aqueous solution model where water must always be included in the constituents of the system. 

The zwitterion/neutral relative free energy was theoretically estimated for tyramine (25) in aqueous solution, modeling pH = 7. The experimentally found ratio is 3.7 at T = 25 "C. Using the PCM/MP2/6-31G and the FEP/MC solvation free energy differences, the zwitterionic form was strongly under- and overestimated, respectively [84]. FEP/MC simulations in the same paper pointed out... 

Figure A2.3.17 Theoretical (HNC) calculations of the osmotic coefficients for the square well model of an electrolyte compared with experimental data for aqueous solutions at 25°C. The parameters for this model are a = r (Pauling)+ r (Pauling), d = d = 0 and d as indicated in the figure.

Rasaiah J C 1970 Equilibrium properties of ionic solutions the primitive model and its modification for aqueous solutions of the alkali halides at 25°C J. Chem. Phys. 52 704... 

Stillinger F 1973 Structure in aqueous solutions from the standpoint of scaled particle theory J. Solution Chem. 2 141 Widom B 1967 Intermolecular forces and the nature of the liquid state Sc/e/ ce 375 157 Longuet-Higgins H C and Widom B 1964 A rigid sphere model for the melting of argon Mol. Phys. 8 549... 

Alexandridis P and Hatton T A 1995 Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) blook oopolymer surfaotants in aqueous solutions and at interfaoes thermodynamios, struoture, dynamios, modeling Colloids Surf. A 96 1-46... 

Obviously, to model these effects simultaneously becomes a very complex task. Hence, most calculation methods treat the effects which are not directly related to the molecular structure as constant. As an important consequence, prediction models are valid only for the system under investigation. A model for the prediction of the acidity constant pfQ in aqueous solutions cannot be applied to the prediction of pKj values in DMSO solutions. Nevertheless, relationships between different systems might also be quantified. Here, Kamlet s concept of solvatochro-mism, which allows the prediction of solvent-dependent properties with respect to both solute and solvent [1], comes to mind. 

Cramer C j and D G Truhlar 1992. AM1-SM2 and PM3-SM3 Parametrized SCF Solvation Models for Free Energies in Aqueous Solution. Journal of Computer-Aided Molecular Design 6 629-666. 

The aromatic shifts that are induced by 5.1c, 5.If and S.lg on the H-NMR spectrum of SDS, CTAB and Zn(DS)2 have been determined. Zn(DS)2 is used as a model system for Cu(DS)2, which is paramagnetic. The cjkcs and counterion binding for Cu(DS)2 and Zn(DS)2 are similar and it has been demonstrated in Chapter 2 that Zn(II) ions are also capable of coordinating to 5.1, albeit somewhat less efficiently than copper ions. Figure 5.7 shows the results of the shift measurements. For comparison purposes also the data for chalcone (5.4) have been added. This compound has almost no tendency to coordinate to transition-metal ions in aqueous solutions. From Figure 5.7 a number of conclusions can be drawn. (1) The shifts induced by 5.1c on the NMR signals of SDS and CTAB... 

What alkene gives a racemic mixture of (2R 3S) and (2S 3R) 3 bromo 2 butanol on treat ment with Br2 in aqueous solution" Hint Make a molecular model of one of the enantiomeric 3 bromo 2 butanols arrange it in a conformation in which the Br and OH groups are anti to one another then disconnect them )... 

CL Eisher, J-L Chen, J Li, D Bashford, L Noodleman. Density-functional and electrostatic calculations for a model of a manganese superoxide dismutase active site in aqueous solution. J Phys Chem 100 13498-13505, 1996. 

As with resoles, we can use a three-phase model to discuss formation of a novolac. Whereas the resole is activated through the phenol, activation in novolacs occurs with protonation of the aldehyde as depicted in Scheme 12. The reader will note that the starting material for the methylolation has been depicted in hydrated form. The equilibrium level of dissolved formaldehyde gas in a 50% aqueous solution is on the order of one part in 10,000. Thus, the hydrated form is prevalent. Whereas protonation of the hydrate would be expected to promote dehydration, we do not mean to imply that the dehydrated cation is the primary reacting species, though it seems possible. 

Hostomsky, J. and Jones, A.G., 1993c. Ibid., Modelling of calcium carbonate precipitation in the reaction between gaseous carbon dioxide and aqueous solution of calcium hydroxide. Indem. pp. 2055-2059. 

The interactions between water and aqueous solutions and another phase have been modeled in various ways. The most simple models consist of an aqueous system in contact with a hard or soft wall described by... 

Much of the study of kinetics constitutes a study of catalysis. The first goal is the determination of the rate equation, and examples have been given in Chapters 2 and 3, particularly Section 3.3, Model Building. The subsection following this one describes the dependence of rates on pH, and most of this dependence can be ascribed to acid—base catalysis. Here we treat a very simple but widely applicable method for the detection and measurement of general acid-base or nucleophilic catalysis. We consider aqueous solutions where the pH and p/f concepts are well understood, but similar methods can be applied in nonaqueous media. 

One femily of models for systems in non-aqueous solution are referred to as Self-Consistent Reaction Field (SCRF) methods. These methods all model the solvent as a continuum of uniform dielectric constant e the reaction field. The solute is placed into a cavity within the solvent. SCRF approachs differ in how they define the cavity and the reaction field. Several are illustrated below. 

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